In the last two decades, the communication technologies used for supervision and control of critical infrastructures such as the power grid, have been migrating from serial links to Internet-compatible network protocols. Despite this trend, the research community has not explored or measured the unique characteristics of these industrial systems, and as a result, most of these networks remain unstudied. In this paper we perform the first measurement study of a Supervisory Control And Data Acquisition (SCADA) network in the bulk power grid. We develop a new protocol parser that can be used to analyze packets not conforming to standards, find attributes to profile the SCADA network, and identify several outliers which underscore the difficulties in managing a federated network where different devices are under the control of different power companies.